A recent study, published in the journal Leukemia & Lymphoma, assessed the toxicity and effectiveness of a second autologous peripheral blood stem cell transplant (APBSCT) in myeloma patients who relapsed or progressed after an initial APBSCT.

It has become increasingly more common for patients to receive a second APBSCT, either within six months of the first one without any myeloma relapse or progression between transplants – or as a salvage therapy following relapse or progression after the first transplant. This study excluded patients who received tandem transplants.

Even though a second APBSCT is now considered a standard part of treatment, the toxicity associated with the second transplant has not been described thoroughly in previous studies.

Many of the toxicities observed in the study were similar to those following the first transplant. However, 92 percent of the patients temporarily developed grade 3 or 4 non-hematologic toxicities following the second APBSCT, with grade 3 and 4 side effects being severe and life-threatening or disabling, respectively.

Researchers compared these toxicity rates to patients receiving thalidomide (Thalomid), Revlimid (lenalidomide), and Velcade (bortezomib) as a salvage therapy. Fifty to 75 percent of patients receiving these novel therapeutic agents experienced grade 3 or 4 toxicity. Generally, all three agents were associated with grade 3 or 4 myelosuppression (decreased blood cells) in 30 to 50 percent of patients, which could lead to infections or require transfusions. Furthermore, Velcade and thalidomide were associated with grade 3 neuropathy in 8 to 16 percent of patients, and this toxicity may be permanent or disabling.

Other problems were also detected by researchers after the second APBSCT, such as a higher incidence of kidney dysfunction, a delay in platelet engraftment (which resulted in an increased need for platelet transfusion), and a treatment-related mortality of 8 percent, which was higher than the numbers typically seen with an initial autologous transplant or tandem transplant.

The eight-year study also reported a median progression free survival of 12 months and a median overall survival of 19 months after the second APBSCT. By comparison, patients that opted for treatment with thalidomide, Revlimid, or Velcade in lieu of a second transplant experienced a median progression-free survival of 5.5 to 11 months and a median overall survival of 14.6 to 30 months.

Due to the absence of truly comparative trials, it remains difficult to assess the optimal treatment for myeloma patients who have been non-responsive to other therapies.

For more information on the study, please see the study in the journal Leukemia & Lymphoma (abstract).